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136 lines
5.8 KiB
136 lines
5.8 KiB
3 years ago
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<!DOCTYPE html>
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<html lang="zh">
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<head>
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<meta charset="utf-8" />
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<base href="../../../" />
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<script src="page.js"></script>
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<link type="text/css" rel="stylesheet" href="page.css" />
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</head>
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<body>
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<h1>[name]</h1>
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<p class="desc">
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一个包含 [page:BufferGeometry BufferGeometry] 实例的实用方法的类。
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</p>
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<h2>方法</h2>
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<h3>[method:Object computeMikkTSpaceTangents]( [param:BufferGeometry geometry], [param:Object MikkTSpace], [param:Boolean negateSign] = true )</h3>
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<ul>
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<li>geometry -- Instance of [page:BufferGeometry].</li>
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<li>MikkTSpace -- Instance of <i>examples/jsm/libs/mikktspace.module.js</i>, or <i>mikktspace</i> npm package. Await <i>MikkTSpace.ready</i> before use.
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<li>negateSign -- Whether to negate the sign component (.w) of each tangent. Required for normal map conventions in some formats, including glTF.</li>
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</ul>
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<p>
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Computes vertex tangents using the [link:http://www.mikktspace.com/ MikkTSpace] algorithm.
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MikkTSpace generates the same tangents consistently, and is used in most modelling tools and
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normal map bakers. Use MikkTSpace for materials with normal maps, because inconsistent
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tangents may lead to subtle visual issues in the normal map, particularly around mirrored
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UV seams.
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</p>
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<p>
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In comparison to this method, [page:BufferGeometry.computeTangents] (a
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custom algorithm) generates tangents that probably will not match the tangents
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in other software. The custom algorithm is sufficient for general use with a
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[page:ShaderMaterial], and may be faster than MikkTSpace.
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</p>
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<p>
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Returns the original [page:BufferGeometry]. Indexed geometries will be de-indexed.
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Requires position, normal, and uv attributes.
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</p>
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<h3>[method:Object computeMorphedAttributes]( [param:Mesh | Line | Points object] )</h3>
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<p>
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object -- Instance of [page:Mesh Mesh] | [page:Line Line] | [page:Points Points].<br /><br />
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Returns the current attributes (Position and Normal) of a morphed/skinned [page:Object3D Object3D] whose geometry is a
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[page:BufferGeometry BufferGeometry], together with the original ones: An Object with 4 properties:
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`positionAttribute`, `normalAttribute`, `morphedPositionAttribute` and `morphedNormalAttribute`.
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Helpful for Raytracing or Decals (i.e. a [page:DecalGeometry DecalGeometry] applied to a morphed Object
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with a [page:BufferGeometry BufferGeometry] will use the original BufferGeometry, not the morphed/skinned one,
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generating an incorrect result.
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Using this function to create a shadow Object3D the DecalGeometry can be correctly generated).
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</p>
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<h3>[method:Number estimateBytesUsed]( [param:BufferGeometry geometry] )</h3>
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<p>
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geometry -- 通过 [page:BufferGeometry BufferGeometry] 的实例来估计内存使用情况。<br /><br />
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返回所有用于表示几何体的属性所占用的字节数。
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</p>
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<h3>[method:InterleavedBufferAttribute interleaveAttributes]( [param:Array attributes] )</h3>
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<p>
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attributes -- 由 [page:BufferAttribute BufferAttribute] 实例组成的数组。<br /><br />
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交叉存储一组属性并返回一个新的对应属性数组，这些属性共享一个 InterleavedBuffer 实例。所有属性都必须兼容的该类型。如果合并不成功，则该方法返回 null 。
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</p>
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<h3>[method:BufferAttribute mergeBufferAttributes]( [param:Array attributes] )</h3>
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<p>
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attributes -- 由 [page:BufferAttribute BufferAttribute] 实例组成的数组。<br /><br />
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将一组属性合并为一个单一的实例。所有几何体都必须兼容该属性，不支持 [page:InterleavedBufferAttribute InterleavedBufferAttributes] 。
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如果合并不成功，则该方法返回 null 。
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</p>
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<h3>[method:BufferGeometry mergeBufferGeometries]( [param:Array geometries], [param:Boolean useGroups] )</h3>
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<p>
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geometries -- 由 [page:BufferGeometry BufferGeometry] 实例的数组。<br />
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useGroups -- 是否要为了合并几何体而产生组。<br /><br />
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将一组几何体合并到一个实例中。所有几何体都必须兼容该属性。
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如果合并不成功，则该方法返回 null。
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</p>
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<h3>[method:BufferGeometry mergeGroups]( [param:BufferGeometry geometry] )</h3>
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<p>
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geometry -- Instance of [page:BufferGeometry BufferGeometry] to merge the groups of.<br /><br />
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Merges the [page:BufferGeometry.groups groups] for the given geometry.
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</p>
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<h3>[method:BufferGeometry mergeVertices]( [param:BufferGeometry geometry], [param:Number tolerance] )</h3>
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<p>
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geometry -- 用于合并顶点的 [page:BufferGeometry BufferGeometry] 实例。<br />
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tolerance -- 要合并的顶点属性之间允许的最大差异。 默认为 1e-4。<br /><br />
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返回一个新的 [page:BufferGeometry BufferGeometry] ，其中包含将所有（在容差范围内的）具有相似属性的顶点合并而成的顶点。
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</p>
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<h3>[method:BufferGeometry toCreasedNormals]( [param:BufferGeometry geometry], [param:Number creaseAngle] )</h3>
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<p>
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geometry -- The input geometry. <br />
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creaseAngle -- The crease angle.
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</p>
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<p>
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Creates a new, non-indexed geometry with smooth normals everywhere except faces that meet at an angle greater than the crease angle.
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</p>
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<h3>[method:BufferGeometry toTrianglesDrawMode]( [param:BufferGeometry geometry], [param:TrianglesDrawMode drawMode] )</h3>
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<p>
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geometry -- Instance of [page:BufferGeometry BufferGeometry].<br />
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drawMode -- The draw mode of the given geometry. Valid inputs are `THREE.TriangleStripDrawMode` and `THREE.TriangleFanDrawMode`.<br /><br />
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Returns a new indexed geometry based on `THREE.TrianglesDrawMode` draw mode. This mode corresponds to the `gl.TRIANGLES` WebGL primitive.
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</p>
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<h2>Source</h2>
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<p>
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[link:https://github.com/mrdoob/three.js/blob/master/examples/jsm/utils/BufferGeometryUtils.js examples/jsm/utils/BufferGeometryUtils.js]
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</p>
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</body>
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</html>
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